1. Field of the Invention
The present invention relates to a terminal structure of a coil device, and is suitably applied, for example, to a terminal structure of a coil device in which a rectangular conductive wire having a flattened sectional shape is wound.
2. Description of Related Art
Conventionally, for example, a coil device which is incorporated into a driving unit that drives a valve body of an injector, is known (see, for example, JP-A-2008-270242). This type of coil device includes a coil formed as a result of winding a conductive wire around a bobbin, and a terminal to which an end of the conductive wire taken out from the coil is connected. This terminal includes a terminal structure having a folded piece that temporarily calks the end of the conductive wire before the end of the wire is coupled electrically to the terminal by fusing.
In recent years, improvement in winding efficiency is required for downsizing or improvement in magnetic properties of the coil device.
According to the device described in the publication of JP-A-2008-270242 as a type of such a terminal structure of the coil device, a shape of the folded piece for joining by fusing the above-described end of the wire of the coil that uses a rectangular conductive wire after temporarily calking this end, is proposed. By virtue of this technology, because a rectangular conductive wire having a rectangular shape in cross section is used for the coil, the space factor of the wire in a coil accommodating space of the bobbin becomes high, and eventually the winding efficiency is improved.
The folded piece is bent over to be folded back from a first planar portion of a terminal body, and includes a second planar portion such that the above end of the wire is placed between the first planar portion and the second planar portion.
However, in the above conventional technology of JP-A-2008-270242, because of the use of the rectangular conductive wire having a more flattened shape in cross section than a round conductive wire, it is difficult to bring the first and second planar portions in to contact evenly with both flat surfaces of the rectangular conductive wire by deforming the second planar portion of the folded piece through the calking. In other words, the conductive wire may be insufficiently calked depending on an insertion position of the end of the rectangular conductive wire, which is inserted between the first and second planar portions. There is concern that the conductive wire may fall out or the rectangular conductive wire may move at the time of the fusing joint to make a joining state unstable as a result of the insufficient calking of the wire. The excessively unstable joining state decreases the reliance on conductivity.